Dramatic change of FeLoBAL SDSS J1632+4504 Kentaro Aoki Subaru - PowerPoint PPT Presentation

Dramatic change of FeLoBAL SDSS J1632+4504 Kentaro Aoki Subaru Telescope & Toru Misawa RIKEN Spectral B4 variability of NAL & mini-BAL

SDSS J1723+5553 2 Dramatic change of FeLoBAL SDSS J1632+4204 What are BAL quasars ? • Broad absorption line (BAL) quasars show broad (1000 - 10000 km/s) blueshifted absorption from ions. • 10 - 20 % of all quasars are BAL quasars. JH -band spectrum Joint Subaru-Gemini Conference 2009 May

3 Dramatic change of FeLoBAL SDSS J1632+4204 • divided into three observation subtypes ✓ High-ionization BAL quasars (HiBAL) - Ly α , N V, Si IV and C IV, but no Al III nor Mg II C IV Si IV HiBAL Al III Mg II Joint Subaru-Gemini Conference 2009 May

4 Dramatic change of FeLoBAL SDSS J1632+4204 ✓ Low-ionization BAL quasars (LoBAL) - high ionization lines + Al III, Mg II - ~1% of all quasars LoBAL Al III Si IV C IV Joint Subaru-Gemini Conference 2009 May

5 Dramatic change of FeLoBAL SDSS J1632+4204 ✓ Iron Low-ionization BAL quasars (FeLoBAL) - high ionization lines + Al III, Mg II + Fe II - 0.3% of all quasars. - Some of them have Balmer absorption lines (Aoki et al. 2006, 2007; Hall 2007). FeLoBAL Mg II Fe II Al III Si IV C IV Joint Subaru-Gemini Conference 2009 May

absorption Balmer Search for 6 Dramatic change of FeLoBAL SDSS J1632+4204 SDSS J163255.46+420407.7 Luminosity increased. 2002 April (SDSS) Absorption lines changed. 2008 February (Subaru/FOCAS) Δλ =7 Å 3.4 yrs in quasar’s frame. z=0.725 M i =-24.35 Joint Subaru-Gemini Conference 2009 May

7 Dramatic change of FeLoBAL SDSS J1632+4204 2008 February • remarkably similar to the (grey) quasar composite spectrum composite ( > 3000 Å ). • “blue” as quasar composite. Joint Subaru-Gemini Conference 2009 May

8 Dramatic change of FeLoBAL SDSS J1632+4204 2002 April (black) ‘red’ quasar composite • λ < 4000 Å : many absorption lines Joint Subaru-Gemini Conference 2009 May

2008 Feb. 9 2002 April Dramatic change of FeLoBAL SDSS J1632+4204 Normalized spectra • Mg II, He I: Fe II Mg II Not changed much (< 30%). • Fe II: 80% weak. He I Joint Subaru-Gemini Conference 2009 May

10 Dramatic change of FeLoBAL SDSS J1632+4204 What caused absorption variation ? • covering factor change • ionization/excitation change • both ✓ difficult to measure covering factors by low-resolution spectra. ✓ ionization change is possible because luminosity increased. Joint Subaru-Gemini Conference 2009 May

11 Dramatic change of FeLoBAL SDSS J1632+4204 Density constrain • recombination time is necessary to change ionization. • recombination time is inversely proportional to electron density. t recombination = (n e α ) -1 , α : recombination coefficient α H+ = 5.4 x 10 -13 cm 3 s -1 (7000 Κ ) (Verner & Ferland 1996) • t recombination < 3.4 yrs (=1.1x10 8 s) in quasar’s rest frame. • n e > 1.7 x 10 4 cm -3 Joint Subaru-Gemini Conference 2009 May

12 Dramatic change of FeLoBAL SDSS J1632+4204 Size constrain • size < 3.4 light-year (=1 pc). • Density and size constrains suggest absorption caused by like broad-line region gas. Joint Subaru-Gemini Conference 2009 May

13 Dramatic change of FeLoBAL SDSS J1632+4204 BAL type • SDSS J1632+4204 switched to LoBAL from FeLoBAL. ★ “Bright” SDSS J1632 resembles to “average” quasar. ★ Bright phase may be usual. • Quasars sometimes may become FeLoBALs. FeLoBALs may be quiescent phase. • NGC 4151: Fe II appear/disappear depend on the luminosity (Crenshaw et al. 2000). • Fraction of BAL type may be determined “life” time of absorbing gas. Joint Subaru-Gemini Conference 2009 May

14 Dramatic change of FeLoBAL SDSS J1632+4204 Time variation of BAL • High ionization absorption line (C IV) change only by 30% in 3-6 yrs (Gibson et al. 2008). • SDSS J1632+4204: Fe II absorption decreased by 80%. • Fe II absorption lines in NGC 4151 also anti-correlated with luminosity (Crenshaw et al. 2002). Joint Subaru-Gemini Conference 2009 May

15 Dramatic change of FeLoBAL SDSS J1632+4204 BAL quasar & non-BAL quasar • disk wind model • orientation-dependent “unified” scheme fraction = covering factor Elvis (2000) Joint Subaru-Gemini Conference 2009 May

16 Stratified wind Dramatic change of FeLoBAL SDSS J1632+4204 Elvis (2000) Joint Subaru-Gemini Conference 2009 May

17 Dramatic change of FeLoBAL SDSS J1632+4204 Outflow structure • high-density & low-ionization gas may be surrounded by low-density & high-ionization gas. • Recent simulation shows such structures by instability (Ohsuga et al. 2005). Joint Subaru-Gemini Conference 2009 May

18 Dramatic change of FeLoBAL SDSS J1632+4204 Conclusions • SDSS J1632+4404 showed changes over 3.4 yrs in quasar’s frame ✓ 80% decrease of Fe II absorption line. ✓ < 30% increase of Mg II absorption line. ✓ 40% decrease of He I absorption line. ✓ factor 3 increase of luminosity at 2600 Å . • These changes are possible due to increase of ionization. Joint Subaru-Gemini Conference 2009 May

19 Dramatic change of FeLoBAL SDSS J1632+4204 Conclusions (2) • n e > 1.7 x 10 4 cm -3 , size < 3.4 pc. Related with BLR. • FeLoBALs may be quiescent phase of quasar activity. • Fe II absorption may occur by denser gas than gas produce C IV absorption. “Deep” into time domain (span & • Monitoring observations are interesting and important. frequency) Joint Subaru-Gemini Conference 2009 May

20 Dramatic change of FeLoBAL SDSS J1632+4204 Do you have any questions ? Joint Subaru-Gemini Conference 2009 May